Method and apparatus for port selection in wireless communication systems

ABSTRACT

A method for operating a user equipment (UE) comprises receiving configuration information for a CSI report. The configuration information includes information to: configure a codebook and parameters for the codebook, the codebook comprising a precoding matrix indicator (PMI) indicating a set of components S to represent N 3  precoding matrices, where N 3 ≥1; and partition the PMI into two subsets, a first PMI subset indicating a first subset of components S1 from the set of components S, and a second PMI subset indicating a second subset of components S2 from the set of components S different from the first subset of components S1. The method further comprises determining the CSI report based on the configuration information, the CSI report including the second PMI subset indicating the second subset of components S2, and transmitting the determined CSI report over an uplink (UL) channel.

CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY

This application is a continuation of U.S. patent application Ser. No.17/011,914, filed on Sep. 3, 2020, which claims priority to U.S.Provisional Patent Application No. 62/897,905, filed on Sep. 9, 2019 andU.S. Provisional Patent Application No. 62/902,094, filed on Sep. 18,2019. The content of the above-identified patent documents isincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to wireless communicationsystems and more specifically to channel state information (CSI)parameter configuration in wireless communication systems.

BACKGROUND

Understanding and correctly estimating the channel between a userequipment (UE) and a base station (BS) (e.g., gNode B (gNB)) isimportant for efficient and effective wireless communication. In orderto correctly estimate the DL channel conditions, the gNB may transmit areference signal, e.g., CSI-RS, to the UE for DL channel measurement,and the UE may report (e.g., feedback) information about channelmeasurement, e.g., CSI, to the gNB. With this DL channel measurement,the gNB is able to select appropriate communication parameters toefficiently and effectively perform wireless data communication with theUE.

SUMMARY

Embodiments of the present disclosure provide methods and apparatuses toenable channel state information (CSI) reporting in a wirelesscommunication system.

In one embodiment, a UE for CSI reporting in a wireless communicationsystem is provided. The UE includes a transceiver configured to receiveconfiguration information for a CSI report, where the configurationinformation includes information to: configure a codebook and parametersfor the codebook, the codebook comprising a precoding matrix indicator(PMI) indicating a set of components S to represent N₃ precodingmatrices, where N₃≥1; and partition the PMI into two subsets, a firstPMI subset indicating a first subset of components S1 from the set ofcomponents S, and a second PMI subset indicating a second subset ofcomponents S2 from the set of components S different from the firstsubset of components S1. The UE further includes a processor operablyconnected to the transceiver. The processor is configured to determinethe CSI report based on the configuration information, the CSI reportincluding the second PMI subset indicating the second subset ofcomponents S2. The transceiver is further configured to transmit thedetermined CSI report over an uplink (UL) channel.

In another embodiment, a BS in a wireless communication system isprovided. The BS includes a processor configured to generateconfiguration information for a channel state information (CSI) report,where the configuration information includes information to: configure acodebook and parameters for the codebook, the codebook comprising aprecoding matrix indicator (PMI) indicating a set of components S torepresent N₃ precoding matrices, where N₃≥1, and partition the PMI intotwo subsets, a first PMI subset indicating a first subset of componentsS1 from the set of components S, and a second PMI subset indicating asecond subset of components S2 from the set of components S differentfrom the first subset of components S1. The BS further includes atransceiver operably connected to the processor. The transceiverconfigured to: transmit the configuration information for the CSIreport; and receive the CSI report over an uplink (UL) channel, the CSIreport including the second PMI subset indicating the second subset ofcomponents S2.

In yet another embodiment, a method for operating a UE is provided. Themethod comprises: receiving configuration information for a CSI report,the configuration information includes information to: configure acodebook and parameters for the codebook, the codebook comprising aprecoding matrix indicator (PMI) indicating a set of components S torepresent N₃ precoding matrices, where N₃≥1; and partition the PMI intotwo subsets, a first PMI subset indicating a first subset of componentsS1 from the set of components S, and a second PMI subset indicating asecond subset of components S2 from the set of components S differentfrom the first subset of components S1. The method further comprisesdetermining the CSI report based on the configuration information, theCSI report including the second PMI subset indicating the second subsetof components S2; and transmitting the determined CSI report over anuplink (UL) channel.

Other technical features may be readily apparent to one skilled in theart from the following figures, descriptions, and claims.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document. The term “couple” and its derivativesrefer to any direct or indirect communication between two or moreelements, whether or not those elements are in physical contact with oneanother. The terms “transmit,” “receive,” and “communicate,” as well asderivatives thereof, encompass both direct and indirect communication.The terms “include” and “comprise,” as well as derivatives thereof, meaninclusion without limitation. The term “or” is inclusive, meaningand/or. The phrase “associated with,” as well as derivatives thereof,means to include, be included within, interconnect with, contain, becontained within, connect to or with, couple to or with, be communicablewith, cooperate with, interleave, juxtapose, be proximate to, be boundto or with, have, have a property of, have a relationship to or with, orthe like. The term “controller” means any device, system or part thereofthat controls at least one operation. Such a controller may beimplemented in hardware or a combination of hardware and software and/orfirmware. The functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely. Thephrase “at least one of,” when used with a list of items, means thatdifferent combinations of one or more of the listed items may be used,and only one item in the list may be needed. For example, “at least oneof: A, B, and C” includes any of the following combinations: A, B, C, Aand B, A and C, B and C, and A and B and C.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for other certain words and phrases are provided throughoutthis patent document. Those of ordinary skill in the art shouldunderstand that in many if not most instances, such definitions apply toprior as well as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates an example wireless network according to embodimentsof the present disclosure;

FIG. 2 illustrates an example gNB according to embodiments of thepresent disclosure;

FIG. 3 illustrates an example UE according to embodiments of the presentdisclosure;

FIG. 4A illustrates a high-level diagram of an orthogonal frequencydivision multiple access transmit path according to embodiments of thepresent disclosure;

FIG. 4B illustrates a high-level diagram of an orthogonal frequencydivision multiple access receive path according to embodiments of thepresent disclosure;

FIG. 5 illustrates a transmitter block diagram for a PDSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 6 illustrates a receiver block diagram for a PDSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 7 illustrates a transmitter block diagram for a PUSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 8 illustrates a receiver block diagram for a PUSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 9 illustrates an example network configuration according toembodiments of the present disclosure;

FIG. 10 illustrates an example multiplexing of two slices according toembodiments of the present disclosure;

FIG. 11 illustrates an example antenna blocks according to embodimentsof the present disclosure;

FIG. 12 illustrates an antenna port layout according to embodiments ofthe present disclosure;

FIG. 13 illustrates a 3D grid of oversampled DFT beams according toembodiments of the present disclosure;

FIG. 14 illustrates a flow chart of a method for operating a UE for CSIreporting in a wireless communication system, as may be performed by aUE, according to embodiments of the present disclosure; and

FIG. 15 illustrates a flow chart of a method for receiving a CSIfeedback, as may be performed by a BS, according to embodiments of thepresent disclosure.

DETAILED DESCRIPTION

FIG. 1 through FIG. 15 , discussed below, and the various embodimentsused to describe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

The following documents and standards descriptions are herebyincorporated by reference into the present disclosure as if fully setforth herein: 3GPP TS 36.211 v16.2.0, “E-UTRA, Physical channels andmodulation” (herein “REF 1”); 3GPP TS 36.212 v16.2.0, “E-UTRA,Multiplexing and Channel coding” (herein “REF 2”); 3GPP TS 36.213v16.2.0, “E-UTRA, Physical Layer Procedures” (herein “REF 3”); 3GPP TS36.321 v16.2.0, “E-UTRA, Medium Access Control (MAC) protocolspecification” (herein “REF 4”); 3GPP TS 36.331 v16.2.0, “E-UTRA, RadioResource Control (RRC) protocol specification” (herein “REF 5”); 3GPP TR22.891 v14.2.0 (herein “REF 6”); 3GPP TS 38.212 v16.2.0, “E-UTRA, NR,Multiplexing and channel coding” (herein “REF 7”); 3GPP TS 38.214v16.2.0, “E-UTRA, NR, Physical layer procedures for data” (herein “REF8”); and 3GPP TS 38.213 v16.2.0, “E-UTRA, NR, Physical Layer Proceduresfor control” (herein “REF 9”).

Aspects, features, and advantages of the disclosure are readily apparentfrom the following detailed description, simply by illustrating a numberof particular embodiments and implementations, including the best modecontemplated for carrying out the disclosure. The disclosure is alsocapable of other and different embodiments, and its several details canbe modified in various obvious respects, all without departing from thespirit and scope of the disclosure. Accordingly, the drawings anddescription are to be regarded as illustrative in nature, and not asrestrictive. The disclosure is illustrated by way of example, and not byway of limitation, in the figures of the accompanying drawings.

In the following, for brevity, both FDD and TDD are considered as theduplex method for both DL and UL signaling.

Although exemplary descriptions and embodiments to follow assumeorthogonal frequency division multiplexing (OFDM) or orthogonalfrequency division multiple access (OFDMA), the present disclosure canbe extended to other OFDM-based transmission waveforms or multipleaccess schemes such as filtered OFDM (F-OFDM).

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a “beyond 4G network” or a“post LTE system.”

The 5G communication system is considered to be implemented in higherfrequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higherdata rates or in lower frequency bands, such as below 6 GHz, to enablerobust coverage and mobility support. To decrease propagation loss ofthe radio waves and increase the transmission coverage, the beamforming,massive multiple-input multiple-output (MIMO), full dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques and the like are discussed in 5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud radioaccess networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul communication, moving network,cooperative communication, coordinated multi-points (CoMP) transmissionand reception, interference mitigation and cancellation and the like.

FIGS. 1-4B below describe various embodiments implemented in wirelesscommunications systems and with the use of orthogonal frequency divisionmultiplexing (OFDM) or orthogonal frequency division multiple access(OFDMA) communication techniques. The descriptions of FIGS. 1-3 are notmeant to imply physical or architectural limitations to the manner inwhich different embodiments may be implemented. Different embodiments ofthe present disclosure may be implemented in any suitably-arrangedcommunications system. The present disclosure covers several componentswhich can be used in conjunction or in combination with one another, orcan operate as standalone schemes.

FIG. 1 illustrates an example wireless network according to embodimentsof the present disclosure. The embodiment of the wireless network shownin FIG. 1 is for illustration only. Other embodiments of the wirelessnetwork 100 could be used without departing from the scope of thisdisclosure.

As shown in FIG. 1 , the wireless network includes a gNB 101, a gNB 102,and a gNB 103. The gNB 101 communicates with the gNB 102 and the gNB103. The gNB 101 also communicates with at least one network 130, suchas the Internet, a proprietary Internet Protocol (IP) network, or otherdata network.

The gNB 102 provides wireless broadband access to the network 130 for afirst plurality of user equipments (UEs) within a coverage area 120 ofthe gNB 102. The first plurality of UEs includes a UE 111, which may belocated in a small business; a UE 112, which may be located in anenterprise (E); a UE 113, which may be located in a WiFi hotspot (HS); aUE 114, which may be located in a first residence (R); a UE 115, whichmay be located in a second residence (R); and a UE 116, which may be amobile device (M), such as a cell phone, a wireless laptop, a wirelessPDA, or the like. The gNB 103 provides wireless broadband access to thenetwork 130 for a second plurality of UEs within a coverage area 125 ofthe gNB 103. The second plurality of UEs includes the UE 115 and the UE116. In some embodiments, one or more of the gNBs 101-103 maycommunicate with each other and with the UEs 111-116 using 5G, LTE,LTE-A, WiMAX, WiFi, or other wireless communication techniques.

Depending on the network type, the term “base station” or “BS” can referto any component (or collection of components) configured to providewireless access to a network, such as transmit point (TP),transmit-receive point (TRP), an enhanced base station (eNodeB or eNB),a 5G base station (gNB), a macrocell, a femtocell, a WiFi access point(AP), or other wirelessly enabled devices. Base stations may providewireless access in accordance with one or more wireless communicationprotocols, e.g., 5G 3GPP new radio interface/access (NR), long termevolution (LTE), LTE advanced (LTE-A), high speed packet access (HSPA),Wi-Fi 802.11a/b/g/n/ac, etc. For the sake of convenience, the terms “BS”and “TRP” are used interchangeably in this patent document to refer tonetwork infrastructure components that provide wireless access to remoteterminals. Also, depending on the network type, the term “userequipment” or “UE” can refer to any component such as “mobile station,”“subscriber station,” “remote terminal,” “wireless terminal,” “receivepoint,” or “user device.” For the sake of convenience, the terms “userequipment” and “UE” are used in this patent document to refer to remotewireless equipment that wirelessly accesses a BS, whether the UE is amobile device (such as a mobile telephone or smartphone) or is normallyconsidered a stationary device (such as a desktop computer or vendingmachine).

Dotted lines show the approximate extents of the coverage areas 120 and125, which are shown as approximately circular for the purposes ofillustration and explanation only. It should be clearly understood thatthe coverage areas associated with gNBs, such as the coverage areas 120and 125, may have other shapes, including irregular shapes, dependingupon the configuration of the gNBs and variations in the radioenvironment associated with natural and man-made obstructions.

As described in more detail below, one or more of the UEs 111-116include circuitry, programing, or a combination thereof, for receivingconfiguration information for a CSI feedback, generating the CSIfeedback, and transmitting the CSI feedback in a wireless communicationsystem. In certain embodiments, one or more of the gNBs 101-103 includescircuitry, programing, or a combination thereof, for generatingconfiguration information for a CSI feedback, transmitting theconfiguration information, and receiving the CSI feedback in a wirelesscommunication system.

Although FIG. 1 illustrates one example of a wireless network, variouschanges may be made to FIG. 1 . For example, the wireless network couldinclude any number of gNBs and any number of UEs in any suitablearrangement. Also, the gNB 101 could communicate directly with anynumber of UEs and provide those UEs with wireless broadband access tothe network 130. Similarly, each gNB 102-103 could communicate directlywith the network 130 and provide UEs with direct wireless broadbandaccess to the network 130. Further, the gNBs 101, 102, and/or 103 couldprovide access to other or additional external networks, such asexternal telephone networks or other types of data networks.

FIG. 2 illustrates an example gNB 102 according to embodiments of thepresent disclosure. The embodiment of the gNB 102 illustrated in FIG. 2is for illustration only, and the gNB s 101 and 103 of FIG. 1 could havethe same or similar configuration. However, gNB s come in a wide varietyof configurations, and FIG. 2 does not limit the scope of thisdisclosure to any particular implementation of a gNB.

As shown in FIG. 2 , the gNB 102 includes multiple antennas 205 a-205 n,multiple RF transceivers 210 a-210 n, transmit (TX) processing circuitry215, and receive (RX) processing circuitry 220. The gNB 102 alsoincludes a controller/processor 225, a memory 230, and a backhaul ornetwork interface 235.

The RF transceivers 210 a-210 n receive, from the antennas 205 a-205 n,incoming RF signals, such as signals transmitted by UEs in the network100. The RF transceivers 210 a-210 n down-convert the incoming RFsignals to generate IF or baseband signals. The IF or baseband signalsare sent to the RX processing circuitry 220, which generates processedbaseband signals by filtering, decoding, and/or digitizing the basebandor IF signals. The RX processing circuitry 220 transmits the processedbaseband signals to the controller/processor 225 for further processing.

The TX processing circuitry 215 receives analog or digital data (such asvoice data, web data, e-mail, or interactive video game data) from thecontroller/processor 225. The TX processing circuitry 215 encodes,multiplexes, and/or digitizes the outgoing baseband data to generateprocessed baseband or IF signals. The RF transceivers 210 a-210 nreceive the outgoing processed baseband or IF signals from the TXprocessing circuitry 215 and up-converts the baseband or IF signals toRF signals that are transmitted via the antennas 205 a-205 n.

The controller/processor 225 can include one or more processors or otherprocessing devices that control the overall operation of the gNB 102.For example, the controller/processor 225 could control the reception offorward channel signals and the transmission of reverse channel signalsby the RF transceivers 210 a-210 n, the RX processing circuitry 220, andthe TX processing circuitry 215 in accordance with well-knownprinciples. The controller/processor 225 could support additionalfunctions as well, such as more advanced wireless communicationfunctions.

For instance, the controller/processor 225 could support beam forming ordirectional routing operations in which outgoing signals from multipleantennas 205 a-205 n are weighted differently to effectively steer theoutgoing signals in a desired direction. Any of a wide variety of otherfunctions could be supported in the gNB 102 by the controller/processor225.

The controller/processor 225 is also capable of executing programs andother processes resident in the memory 230, such as an OS. Thecontroller/processor 225 can move data into or out of the memory 230 asrequired by an executing process.

The controller/processor 225 is also coupled to the backhaul or networkinterface 235. The backhaul or network interface 235 allows the gNB 102to communicate with other devices or systems over a backhaul connectionor over a network. The interface 235 could support communications overany suitable wired or wireless connection(s). For example, when the gNB102 is implemented as part of a cellular communication system (such asone supporting 5G, LTE, or LTE-A), the interface 235 could allow the gNB102 to communicate with other gNBs over a wired or wireless backhaulconnection. When the gNB 102 is implemented as an access point, theinterface 235 could allow the gNB 102 to communicate over a wired orwireless local area network or over a wired or wireless connection to alarger network (such as the Internet). The interface 235 includes anysuitable structure supporting communications over a wired or wirelessconnection, such as an Ethernet or RF transceiver.

The memory 230 is coupled to the controller/processor 225. Part of thememory 230 could include a RAM, and another part of the memory 230 couldinclude a Flash memory or other ROM.

Although FIG. 2 illustrates one example of gNB 102, various changes maybe made to FIG. 2 . For example, the gNB 102 could include any number ofeach component shown in FIG. 2 . As a particular example, an accesspoint could include a number of interfaces 235, and thecontroller/processor 225 could support routing functions to route databetween different network addresses. As another particular example,while shown as including a single instance of TX processing circuitry215 and a single instance of RX processing circuitry 220, the gNB 102could include multiple instances of each (such as one per RFtransceiver). Also, various components in FIG. 2 could be combined,further subdivided, or omitted and additional components could be addedaccording to particular needs.

FIG. 3 illustrates an example UE 116 according to embodiments of thepresent disclosure. The embodiment of the UE 116 illustrated in FIG. 3is for illustration only, and the UEs 111-115 of FIG. 1 could have thesame or similar configuration. However, UEs come in a wide variety ofconfigurations, and FIG. 3 does not limit the scope of this disclosureto any particular implementation of a UE.

As shown in FIG. 3 , the UE 116 includes an antenna 305, a radiofrequency (RF) transceiver 310, TX processing circuitry 315, amicrophone 320, and receive (RX) processing circuitry 325. The UE 116also includes a speaker 330, a processor 340, an input/output (I/O)interface (IF) 345, a touchscreen 350, a display 355, and a memory 360.The memory 360 includes an operating system (OS) 361 and one or moreapplications 362.

The RF transceiver 310 receives, from the antenna 305, an incoming RFsignal transmitted by a gNB of the network 100. The RF transceiver 310down-converts the incoming RF signal to generate an intermediatefrequency (IF) or baseband signal. The IF or baseband signal is sent tothe RX processing circuitry 325, which generates a processed basebandsignal by filtering, decoding, and/or digitizing the baseband or IFsignal. The RX processing circuitry 325 transmits the processed basebandsignal to the speaker 330 (such as for voice data) or to the processor340 for further processing (such as for web browsing data).

The TX processing circuitry 315 receives analog or digital voice datafrom the microphone 320 or other outgoing baseband data (such as webdata, e-mail, or interactive video game data) from the processor 340.The TX processing circuitry 315 encodes, multiplexes, and/or digitizesthe outgoing baseband data to generate a processed baseband or IFsignal. The RF transceiver 310 receives the outgoing processed basebandor IF signal from the TX processing circuitry 315 and up-converts thebaseband or IF signal to an RF signal that is transmitted via theantenna 305.

The processor 340 can include one or more processors or other processingdevices and execute the OS 361 stored in the memory 360 in order tocontrol the overall operation of the UE 116. For example, the processor340 could control the reception of forward channel signals and thetransmission of reverse channel signals by the RF transceiver 310, theRX processing circuitry 325, and the TX processing circuitry 315 inaccordance with well-known principles. In some embodiments, theprocessor 340 includes at least one microprocessor or microcontroller.

The processor 340 is also capable of executing other processes andprograms resident in the memory 360, such as processes for determining aCSI report based on received configuration information, where theconfiguration information includes information to: configure a codebookand parameters for the codebook, the codebook comprising a precodingmatrix indicator (PMI) indicating a set of components S to represent N₃precoding matrices, where N₃≥1; and partition the PMI into two subsets,a first PMI subset indicating a first subset of components S1 from theset of components S, and a second PMI subset indicating a second subsetof components S2 from the set of components S different from the firstsubset of components S1. The processor 340 can move data into or out ofthe memory 360 as required by an executing process. In some embodiments,the processor 340 is configured to execute the applications 362 based onthe OS 361 or in response to signals received from gNBs or an operator.The processor 340 is also coupled to the I/O interface 345, whichprovides the UE 116 with the ability to connect to other devices, suchas laptop computers and handheld computers. The I/O interface 345 is thecommunication path between these accessories and the processor 340.

The processor 340 is also coupled to the touchscreen 350 and the display355. The operator of the UE 116 can use the touchscreen 350 to enterdata into the UE 116. The display 355 may be a liquid crystal display,light emitting diode display, or other display capable of rendering textand/or at least limited graphics, such as from web sites.

The memory 360 is coupled to the processor 340. Part of the memory 360could include a random access memory (RAM), and another part of thememory 360 could include a Flash memory or other read-only memory (ROM).

Although FIG. 3 illustrates one example of UE 116, various changes maybe made to FIG. 3 . For example, various components in FIG. 3 could becombined, further subdivided, or omitted and additional components couldbe added according to particular needs. As a particular example, theprocessor 340 could be divided into multiple processors, such as one ormore central processing units (CPUs) and one or more graphics processingunits (GPUs). Also, while FIG. 3 illustrates the UE 116 configured as amobile telephone or smartphone, UEs could be configured to operate asother types of mobile or stationary devices.

FIG. 4A is a high-level diagram of transmit path circuitry. For example,the transmit path circuitry may be used for an orthogonal frequencydivision multiple access (OFDMA) communication. FIG. 4B is a high-leveldiagram of receive path circuitry. For example, the receive pathcircuitry may be used for an orthogonal frequency division multipleaccess (OFDMA) communication. In FIGS. 4A and 4B, for downlinkcommunication, the transmit path circuitry may be implemented in a basestation (gNB) 102 or a relay station, and the receive path circuitry maybe implemented in a user equipment (e.g., user equipment 116 of FIG. 1). In other examples, for uplink communication, the receive pathcircuitry 450 may be implemented in a base station (e.g., gNB 102 ofFIG. 1 ) or a relay station, and the transmit path circuitry may beimplemented in a user equipment (e.g., user equipment 116 of FIG. 1 ).

Transmit path circuitry comprises channel coding and modulation block405, serial-to-parallel (S-to-P) block 410, Size N Inverse Fast FourierTransform (IFFT) block 415, parallel-to-serial (P-to-S) block 420, addcyclic prefix block 425, and up-converter (UC) 430. Receive pathcircuitry 450 comprises down-converter (DC) 455, remove cyclic prefixblock 460, serial-to-parallel (S-to-P) block 465, Size N Fast FourierTransform (FFT) block 470, parallel-to-serial (P-to-S) block 475, andchannel decoding and demodulation block 480.

At least some of the components in FIGS. 4A 400 and 4B 450 may beimplemented in software, while other components may be implemented byconfigurable hardware or a mixture of software and configurablehardware. In particular, it is noted that the FFT blocks and the IFFTblocks described in this disclosure document may be implemented asconfigurable software algorithms, where the value of Size N may bemodified according to the implementation.

Furthermore, although this disclosure is directed to an embodiment thatimplements the Fast Fourier Transform and the Inverse Fast FourierTransform, this is by way of illustration only and may not be construedto limit the scope of the disclosure. It may be appreciated that in analternate embodiment of the present disclosure, the Fast FourierTransform functions and the Inverse Fast Fourier Transform functions mayeasily be replaced by discrete Fourier transform (DFT) functions andinverse discrete Fourier transform (IDFT) functions, respectively. Itmay be appreciated that for DFT and IDFT functions, the value of the Nvariable may be any integer number (i.e., 1, 4, 3, 4, etc.), while forFFT and IFFT functions, the value of the N variable may be any integernumber that is a power of two (i.e., 1, 2, 4, 8, 16, etc.).

In transmit path circuitry 400, channel coding and modulation block 405receives a set of information bits, applies coding (e.g., LDPC coding)and modulates (e.g., quadrature phase shift keying (QPSK) or quadratureamplitude modulation (QAM)) the input bits to produce a sequence offrequency-domain modulation symbols. Serial-to-parallel block 410converts (i.e., de-multiplexes) the serial modulated symbols to paralleldata to produce N parallel symbol streams where N is the IFFT/FFT sizeused in BS 102 and UE 116. Size N IFFT block 415 then performs an IFFToperation on the N parallel symbol streams to produce time-domain outputsignals. Parallel-to-serial block 420 converts (i.e., multiplexes) theparallel time-domain output symbols from Size N IFFT block 415 toproduce a serial time-domain signal. Add cyclic prefix block 425 theninserts a cyclic prefix to the time-domain signal. Finally, up-converter430 modulates (i.e., up-converts) the output of add cyclic prefix block425 to RF frequency for transmission via a wireless channel. The signalmay also be filtered at baseband before conversion to RF frequency.

The transmitted RF signal arrives at the UE 116 after passing throughthe wireless channel, and reverse operations to those at gNB 102 areperformed. Down-converter 455 down-converts the received signal tobaseband frequency and removes cyclic prefix block 460, and removes thecyclic prefix to produce the serial time-domain baseband signal.Serial-to-parallel block 465 converts the time-domain baseband signal toparallel time-domain signals. Size N FFT block 470 then performs an FFTalgorithm to produce N parallel frequency-domain signals.Parallel-to-serial block 475 converts the parallel frequency-domainsignals to a sequence of modulated data symbols. Channel decoding anddemodulation block 480 demodulates and then decodes the modulatedsymbols to recover the original input data stream.

Each of gNB s 101-103 may implement a transmit path that is analogous totransmitting in the downlink to user equipment 111-116 and may implementa receive path that is analogous to receiving in the uplink from userequipment 111-116. Similarly, each one of user equipment 111-116 mayimplement a transmit path corresponding to the architecture fortransmitting in the uplink to gNB s 101-103 and may implement a receivepath corresponding to the architecture for receiving in the downlinkfrom gNBs 101-103.

5G communication system use cases have been identified and described.Those use cases can be roughly categorized into three different groups.In one example, enhanced mobile broadband (eMBB) is determined to dowith high bits/sec requirement, with less stringent latency andreliability requirements. In another example, ultra reliable and lowlatency (URLL) is determined with less stringent bits/sec requirement.In yet another example, massive machine type communication (mMTC) isdetermined that a number of devices can be as many as 100,000 to 1million per km2, but the reliability/throughput/latency requirementcould be less stringent. This scenario may also involve power efficiencyrequirement as well, in that the battery consumption may be minimized aspossible.

A communication system includes a downlink (DL) that conveys signalsfrom transmission points such as base stations (BSs) or NodeBs to userequipments (UEs) and an Uplink (UL) that conveys signals from UEs toreception points such as NodeBs. A UE, also commonly referred to as aterminal or a mobile station, may be fixed or mobile and may be acellular phone, a personal computer device, or an automated device. AneNodeB, which is generally a fixed station, may also be referred to asan access point or other equivalent terminology. For LTE systems, aNodeB is often referred as an eNodeB.

In a communication system, such as LTE system, DL signals can includedata signals conveying information content, control signals conveying DLcontrol information (DCI), and reference signals (RS) that are alsoknown as pilot signals. An eNodeB transmits data information through aphysical DL shared channel (PDSCH). An eNodeB transmits DCI through aphysical DL control channel (PDCCH) or an Enhanced PDCCH (EPDCCH).

An eNodeB transmits acknowledgement information in response to datatransport block (TB) transmission from a UE in a physical hybrid ARQindicator channel (PHICH). An eNodeB transmits one or more of multipletypes of RS including a UE-common RS (CRS), a channel state informationRS (CSI-RS), or a demodulation RS (DMRS). A CRS is transmitted over a DLsystem bandwidth (BW) and can be used by UEs to obtain a channelestimate to demodulate data or control information or to performmeasurements. To reduce CRS overhead, an eNodeB may transmit a CSI-RSwith a smaller density in the time and/or frequency domain than a CRS.DMRS can be transmitted only in the BW of a respective PDSCH or EPDCCHand a UE can use the DMRS to demodulate data or control information in aPDSCH or an EPDCCH, respectively. A transmission time interval for DLchannels is referred to as a subframe and can have, for example,duration of 1 millisecond.

DL signals also include transmission of a logical channel that carriessystem control information. A BCCH is mapped to either a transportchannel referred to as a broadcast channel (BCH) when the DL signalsconvey a master information block (MIB) or to a DL shared channel(DL-SCH) when the DL signals convey a System Information Block (SIB).Most system information is included in different SIB s that aretransmitted using DL-SCH. A presence of system information on a DL-SCHin a subframe can be indicated by a transmission of a correspondingPDCCH conveying a codeword with a cyclic redundancy check (CRC)scrambled with system information RNTI (SI-RNTI). Alternatively,scheduling information for a SIB transmission can be provided in anearlier SIB and scheduling information for the first SIB (SIB-1) can beprovided by the MIB.

DL resource allocation is performed in a unit of subframe and a group ofphysical resource blocks (PRBs). A transmission BW includes frequencyresource units referred to as resource blocks (RBs). Each RB includesN_(sc) ^(RB) sub-carriers, or resource elements (REs), such as 12 REs. Aunit of one RB over one subframe is referred to as a PRB. A UE can beallocated M_(PDSCH) RBs for a total of M_(sc) ^(PDSCH)=M_(PDSCH)·N_(sc)^(RB) REs for the PDSCH transmission BW.

UL signals can include data signals conveying data information, controlsignals conveying UL control information (UCI), and UL RS. UL RSincludes DMRS and Sounding RS (SRS). A UE transmits DMRS only in a BW ofa respective PUSCH or PUCCH. An eNodeB can use a DMRS to demodulate datasignals or UCI signals. A UE transmits SRS to provide an eNodeB with anUL CSI. A UE transmits data information or UCI through a respectivephysical UL shared channel (PUSCH) or a Physical UL control channel(PUCCH). If a UE needs to transmit data information and UCI in a same ULsubframe, the UE may multiplex both in a PUSCH. UCI includes HybridAutomatic Repeat request acknowledgement (HARQ-ACK) information,indicating correct (ACK) or incorrect (NACK) detection for a data TB ina PDSCH or absence of a PDCCH detection (DTX), scheduling request (SR)indicating whether a UE has data in the UE's buffer, rank indicator(RI), and channel state information (CSI) enabling an eNodeB to performlink adaptation for PDSCH transmissions to a UE. HARQ-ACK information isalso transmitted by a UE in response to a detection of a PDCCH/EPDCCHindicating a release of semi-persistently scheduled PDSCH.

An UL subframe includes two slots. Each slot includes N_(symb) ^(UL)symbols for transmitting data information, UCI, DMRS, or SRS. Afrequency resource unit of an UL system BW is a RB. A UE is allocatedN_(RB) RBs for a total of N_(RB)·N_(sc) ^(RB) REs for a transmission BW.For a PUCCH, N_(RB)=1. A last subframe symbol can be used to multiplexSRS transmissions from one or more UEs. A number of subframe symbolsthat are available for data/UCI/DMRS transmission isN_(symb)=2·(N_(symb) ^(UL)−1)−N_(SRS), where N_(SRS)=1 if a lastsubframe symbol is used to transmit SRS and N_(SRS)=0 otherwise.

FIG. 5 illustrates a transmitter block diagram 500 for a PDSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the transmitter block diagram 500 illustrated in FIG. 5 isfor illustration only. One or more of the components illustrated in FIG.5 can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 5 does not limit the scope of this disclosure to anyparticular implementation of the transmitter block diagram 500.

As shown in FIG. 5 , information bits 510 are encoded by encoder 520,such as a turbo encoder, and modulated by modulator 530, for exampleusing quadrature phase shift keying (QPSK) modulation. A serial toparallel (S/P) converter 540 generates M modulation symbols that aresubsequently provided to a mapper 550 to be mapped to REs selected by atransmission BW selection unit 555 for an assigned PDSCH transmissionBW, unit 560 applies an Inverse fast Fourier transform (IFFT), theoutput is then serialized by a parallel to serial (P/S) converter 570 tocreate a time domain signal, filtering is applied by filter 580, and asignal transmitted 590. Additional functionalities, such as datascrambling, cyclic prefix insertion, time windowing, interleaving, andothers are well known in the art and are not shown for brevity.

FIG. 6 illustrates a receiver block diagram 600 for a PDSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the diagram 600 illustrated in FIG. 6 is for illustrationonly. One or more of the components illustrated in FIG. 6 can beimplemented in specialized circuitry configured to perform the notedfunctions or one or more of the components can be implemented by one ormore processors executing instructions to perform the noted functions.FIG. 6 does not limit the scope of this disclosure to any particularimplementation of the diagram 600.

As shown in FIG. 6 , a received signal 610 is filtered by filter 620,REs 630 for an assigned reception BW are selected by BW selector 635,unit 640 applies a fast Fourier transform (FFT), and an output isserialized by a parallel-to-serial converter 650. Subsequently, ademodulator 660 coherently demodulates data symbols by applying achannel estimate obtained from a DMRS or a CRS (not shown), and adecoder 670, such as a turbo decoder, decodes the demodulated data toprovide an estimate of the information data bits 680. Additionalfunctionalities such as time-windowing, cyclic prefix removal,de-scrambling, channel estimation, and de-interleaving are not shown forbrevity.

FIG. 7 illustrates a transmitter block diagram 700 for a PUSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the block diagram 700 illustrated in FIG. 7 is forillustration only. One or more of the components illustrated in FIG. 5can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 7 does not limit the scope of this disclosure to anyparticular implementation of the block diagram 700.

As shown in FIG. 7 , information data bits 710 are encoded by encoder720, such as a turbo encoder, and modulated by modulator 730. A discreteFourier transform (DFT) unit 740 applies a DFT on the modulated databits, REs 750 corresponding to an assigned PUSCH transmission BW areselected by transmission BW selection unit 755, unit 760 applies an IFFTand, after a cyclic prefix insertion (not shown), filtering is appliedby filter 770 and a signal transmitted 780.

FIG. 8 illustrates a receiver block diagram 800 for a PUSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the block diagram 800 illustrated in FIG. 8 is forillustration only. One or more of the components illustrated in FIG. 8can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 8 does not limit the scope of this disclosure to anyparticular implementation of the block diagram 800.

As shown in FIG. 8 , a received signal 810 is filtered by filter 820.Subsequently, after a cyclic prefix is removed (not shown), unit 830applies a FFT, REs 840 corresponding to an assigned PUSCH reception BWare selected by a reception BW selector 845, unit 850 applies an inverseDFT (IDFT), a demodulator 860 coherently demodulates data symbols byapplying a channel estimate obtained from a DMRS (not shown), a decoder870, such as a turbo decoder, decodes the demodulated data to provide anestimate of the information data bits 880.

In next generation cellular systems, various use cases are envisionedbeyond the capabilities of LTE system. Termed 5G or the fifth generationcellular system, a system capable of operating at sub-6 GHz and above-6GHz (for example, in mmWave regime) becomes one of the requirements. In3GPP TR 22.891, 74 5G use cases have been identified and described;those use cases can be roughly categorized into three different groups.A first group is termed “enhanced mobile broadband (eMBB),” targeted tohigh data rate services with less stringent latency and reliabilityrequirements. A second group is termed “ultra-reliable and low latency(URLL)” targeted for applications with less stringent data raterequirements, but less tolerant to latency. A third group is termed“massive MTC (mMTC)” targeted for large number of low-power deviceconnections such as 1 million per km² with less stringent thereliability, data rate, and latency requirements.

FIG. 9 illustrates an example network configuration 900 according toembodiments of the present disclosure. The embodiment of the networkconfiguration 900 illustrated in FIG. 9 is for illustration only. FIG. 9does not limit the scope of this disclosure to any particularimplementation of the configuration 900.

In order for the 5G network to support such diverse services withdifferent quality of services (QoS), one scheme has been identified in3GPP specification, called network slicing.

As shown in FIG. 9 , an operator's network 910 includes a number ofradio access network(s) 920 (RAN(s)) that are associated with networkdevices such as gNBs 930 a and 930 b, small cell base stations(femto/pico gNBs or Wi-Fi access points) 935 a and 935 b. The network910 can support various services, each represented as a slice.

In the example, an URLL slice 940 a serves UEs requiring URLL servicessuch as cars 945 b, trucks 945 c, smart watches 945 a, and smart glasses945 d. Two mMTC slices 950 a and 950 b serve UEs requiring mMTC servicessuch as power meters 955 a, and temperature control box 955 b. One eMBBslice 960 a serves UEs requiring eMBB services such as cells phones 965a, laptops 965 b, and tablets 965 c. A device configured with two slicescan also be envisioned.

To utilize PHY resources efficiently and multiplex various slices (withdifferent resource allocation schemes, numerologies, and schedulingstrategies) in DL-SCH, a flexible and self-contained frame or subframedesign is utilized.

FIG. 10 illustrates an example multiplexing of two slices 1000 accordingto embodiments of the present disclosure. The embodiment of themultiplexing of two slices 1000 illustrated in FIG. 10 is forillustration only. One or more of the components illustrated in FIG. 10can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 10 does not limit the scope of this disclosure to anyparticular implementation of the multiplexing of two slices 1000.

Two exemplary instances of multiplexing two slices within a commonsubframe or frame are depicted in FIG. 10 . In these exemplaryembodiments, a slice can be composed of one or two transmissioninstances where one transmission instance includes a control (CTRL)component (e.g., 1020 a, 1060 a, 1060 b, 1020 b, or 1060 c) and a datacomponent (e.g., 1030 a, 1070 a, 1070 b, 1030 b, or 1070 c). Inembodiment 1010, the two slices are multiplexed in frequency domainwhereas in embodiment 1050, the two slices are multiplexed in timedomain.

The 3GPP NR specification supports up to 32 CSI-RS antenna ports whichenable a gNB to be equipped with a large number of antenna elements(such as 64 or 128). In this case, a plurality of antenna elements ismapped onto one CSI-RS port. For next generation cellular systems suchas 5G, the maximum number of CSI-RS ports can either remain the same orincrease.

FIG. 11 illustrates an example antenna blocks 1100 according toembodiments of the present disclosure. The embodiment of the antennablocks 1100 illustrated in FIG. 11 is for illustration only. FIG. 11does not limit the scope of this disclosure to any particularimplementation of the antenna blocks 1100.

For mmWave bands, although the number of antenna elements can be largerfor a given form factor, the number of CSI-RS ports—which can correspondto the number of digitally precoded ports—tends to be limited due tohardware constraints (such as the feasibility to install a large numberof ADCs/DACs at mmWave frequencies) as illustrated in FIG. 11 . In thiscase, one CSI-RS port is mapped onto a large number of antenna elementswhich can be controlled by a bank of analog phase shifters. One CSI-RSport can then correspond to one sub-array which produces a narrow analogbeam through analog beamforming. This analog beam can be configured tosweep across a wider range of angles by varying the phase shifter bankacross symbols or subframes. The number of sub-arrays (equal to thenumber of RF chains) is the same as the number of CSI-RS portsN_(CSI-PORT). A digital beamforming unit performs a linear combinationacross N_(CSI-PORT) analog beams to further increase precoding gain.While analog beams are wideband (hence not frequency-selective), digitalprecoding can be varied across frequency sub-bands or resource blocks.

To enable digital precoding, efficient design of CSI-RS is a crucialfactor. For this reason, three types of CSI reporting mechanismcorresponding to three types of CSI-RS measurement behavior aresupported, for example, “CLASS A” CSI reporting which corresponds tonon-precoded CSI-RS, “CLASS B” reporting with K=1 CSI-RS resource whichcorresponds to UE-specific beamformed CSI-RS, and “CLASS B” reportingwith K>1 CSI-RS resources which corresponds to cell-specific beamformedCSI-RS.

For non-precoded (NP) CSI-RS, a cell-specific one-to-one mapping betweenCSI-RS port and TXRU is utilized. Different CSI-RS ports have the samewide beam width and direction and hence generally cell wide coverage.For beamformed CSI-RS, beamforming operation, either cell-specific orUE-specific, is applied on a non-zero-power (NZP) CSI-RS resource (e.g.,comprising multiple ports). At least at a given time/frequency, CSI-RSports have narrow beam widths and hence not cell wide coverage, and atleast from the gNB perspective. At least some CSI-RS port-resourcecombinations have different beam directions.

In scenarios where DL long-term channel statistics can be measuredthrough UL signals at a serving eNodeB, UE-specific BF CSI-RS can bereadily used. This is typically feasible when UL-DL duplex distance issufficiently small. When this condition does not hold, however, some UEfeedback is necessary for the eNodeB to obtain an estimate of DLlong-term channel statistics (or any of representation thereof). Tofacilitate such a procedure, a first BF CSI-RS transmitted withperiodicity T1 (ms) and a second NP CSI-RS transmitted with periodicityT2 (ms), where T1 T2. This approach is termed hybrid CSI-RS. Theimplementation of hybrid CSI-RS is largely dependent on the definitionof CSI process and NZP CSI-RS resource.

In the 3GPP LTE specification, MIMO has been identified as an essentialfeature in order to achieve high system throughput requirements and itwill continue to be the same in NR. One of the key components of a MIMOtransmission scheme is the accurate CSI acquisition at the eNB (or TRP).For MU-MIMO, in particular, the availability of accurate CSI isnecessary in order to guarantee high MU performance. For TDD systems,the CSI can be acquired using the SRS transmission relying on thechannel reciprocity. For FDD systems, on the other hand, the CSI can beacquired using the CSI-RS transmission from the eNB, and CSI acquisitionand feedback from the UE. In legacy FDD systems, the CSI feedbackframework is ‘implicit’ in the form of CQI/PMI/RI derived from acodebook assuming SU transmission from the eNB. Because of the inherentSU assumption while deriving CSI, this implicit CSI feedback isinadequate for MU transmission. Since future (e.g., NR) systems arelikely to be more MU-centric, this SU-MU CSI mismatch will be abottleneck in achieving high MU performance gains. Another issue withimplicit feedback is the scalability with larger number of antenna portsat the eNB. For large number of antenna ports, the codebook design forimplicit feedback is quite complicated, and the designed codebook is notguaranteed to bring justifiable performance benefits in practicaldeployment scenarios (for example, only a small percentage gain can beshown at the most).

In 5G or NR systems, the above-mentioned CSI reporting paradigm from LTEis also supported and referred to as Type I CSI reporting. In additionto Type I, a high-resolution CSI reporting, referred to as Type II CSIreporting, is also supported to provide more accurate CSI information togNB for use cases such as high-order MU-MIMO.

FIG. 12 illustrates an example antenna port layout 1200 according toembodiments of the present disclosure. The embodiment of the antennaport layout 1200 illustrated in FIG. 12 is for illustration only. FIG.12 does not limit the scope of this disclosure to any particularimplementation of the antenna port layout 1200.

As illustrated in FIG. 12 , N₁ and N₂ are the number of antenna portswith the same polarization in the first and second dimensions,respectively. For 2D antenna port layouts, N₁>1, N₂>1, and for 1Dantenna port layouts N₁>1 and N₂=1. Therefore, for a dual-polarizedantenna port layout, the total number of antenna ports is 2N₁N₂.

As described in U.S. Pat. No. 10,659,118, issued May 19, 2020 andentitled “Method and Apparatus for Explicit CSI Reporting in AdvancedWireless Communication Systems,” which is incorporated herein byreference in its entirety, a UE is configured with high-resolution(e.g., Type II) CSI reporting in which the linear combination based TypeII CSI reporting framework is extended to include a frequency dimensionin addition to the first and second antenna port dimensions.

FIG. 13 illustrates a 3D grid 1300 of the oversampled DFT beams (1stport dim., 2nd port dim., freq. dim.) in which

-   -   1st dimension is associated with the 1st port dimension,    -   2nd dimension is associated with the 2nd port dimension, and    -   3rd dimension is associated with the frequency dimension.        The basis sets for 1^(st) and 2^(nd) port domain representation        are oversampled DFT codebooks of length-N₁ and length-N₂,        respectively, and with oversampling factors O₁ and O₂,        respectively. Likewise, the basis set for frequency domain        representation (i.e., 3rd dimension) is an oversampled DFT        codebook of length-N₃ and with oversampling factor O₃. In one        example, O₁=O₂=O₃=4. In another example, the oversampling        factors O_(i) belongs to {2, 4, 8}. In yet another example, at        least one of O₁, O₂, and O₃ is higher layer configured (via RRC        signaling).

A UE is configured with higher layer parameter CodebookType set to‘TypeII-Compression’ or ‘TypeIII’ for an enhanced Type II CSI reportingin which the pre-coders for all subbands (SBs) and for a given layerl=1, . . . , v, where v is the associated RI value, is given by either

$\begin{matrix}{{W^{l} = {{{AC}_{l}B^{H}} = {{{\left\lbrack {a_{0}a_{1}\ldots a_{L - 1}} \right\rbrack\begin{bmatrix}c_{l,0,0} & c_{l,0,1} & \cdots & c_{l,0,{M - 1}} \\c_{l,1,0} & c_{l,1,1} & \cdots & c_{l,1,{M - 1}} \\ \vdots & \vdots & \vdots & \vdots \\c_{l,{L - 1},0} & c_{l,{L - 1},1} & \cdots & c_{l,{L - 1},{M - 1}}\end{bmatrix}}\left\lbrack {b_{0}b_{1}\ldots b_{M - 1}} \right\rbrack^{H}} = {{\sum\limits_{m = 0}^{M - 1}{\sum\limits_{i = 0}^{L - 1}{c_{l,i,m}\left( {a_{i}b_{m}^{H}} \right)}}} = {\sum\limits_{i = 0}^{L - 1}{\sum\limits_{m = 0}^{M - 1}{c_{l,i,m}\left( {a_{i}b_{m}^{H}} \right)}}}}}}},} & \left( {{Eq}.1} \right)\end{matrix}$ or $\begin{matrix}{{W^{l} = {{\begin{bmatrix}A & 0 \\0 & A\end{bmatrix}C_{l}B^{H}} = {{{\begin{bmatrix}{a_{0}a_{1}\ldots a_{L - 1}} & 0 \\0 & {a_{0}a_{1}\ldots a_{L - 1}}\end{bmatrix}\begin{bmatrix}c_{l,0,0} & c_{l,0,1} & \cdots & c_{l,0,{M - 1}} \\c_{l,1,0} & c_{l,1,1} & \cdots & c_{l,1,{M - 1}} \\ \vdots & \vdots & \vdots & \vdots \\c_{l,{L - 1},0} & c_{l,{L - 1},1} & \cdots & c_{l,{L - 1},{M - 1}}\end{bmatrix}}\left\lbrack {b_{0}b_{1}\ldots b_{M - 1}} \right\rbrack^{H}} = \begin{bmatrix}{\sum\limits_{m = 0}^{M - 1}{\sum\limits_{i = 0}^{L - 1}{c_{l,i,m}\left( {a_{i}b_{m}^{H}} \right)}}} \\{\sum\limits_{m = 0}^{M - 1}{\sum\limits_{i = 0}^{L - 1}{c_{l,i,m}\left( {a_{i}b_{m}^{H}} \right)}}}\end{bmatrix}}}},} & \left( {{Eq}.2} \right)\end{matrix}$

where

-   -   N₁ is a number of antenna ports in a first antenna port        dimension,    -   N₂ is a number of antenna ports in a second antenna port        dimension,    -   N₃ is a number of SBs or frequency domain (FD) units/components        for PMI reporting (that comprise the CSI reporting band), which        can be different (e.g., less than) from a number of SBs for CQI        reporting,    -   a_(i) is a 2N₁N₂×1 (Eq. 1) or N₁N₂×1 (Eq. 2) column vector,    -   b_(m) is a N₃×1 column vector,    -   c_(l,i,m) is a complex coefficient.

In a variation, when a subset K<2LM coefficients (where K is eitherfixed, configured by the gNB or reported by the UE), then thecoefficient c_(l,i,m) in precoder equations Eq. 1 or Eq. 2 is replacedwith v_(l,i,m)×c_(l,i,m), where

-   -   v_(l,i,m)=1 if the coefficient c_(l,i,m) is non-zero, hence        reported by the UE according to some embodiments of this        disclosure.    -   v_(l,i,m)=0 otherwise (i.e., c_(l,i,m) is zero, hence not        reported by the UE).        The indication whether v_(l,i,m)=1 or 0 is according to some        embodiments of this disclosure.

In a variation, the precoder equations Eq. 1 or Eq. 2 are respectivelygeneralized to

$\begin{matrix}{W^{l} = {\sum\limits_{i = 0}^{L - 1}{\sum\limits_{m = 0}^{M_{i} - 1}{c_{l,i,m}\left( {a_{i}b_{i,m}^{H}} \right)}}}} & \left( {{Eq}.3} \right)\end{matrix}$ and $\begin{matrix}{{W^{l} = \begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{\sum\limits_{m = 0}^{M_{i} - 1}{c_{l,i,m}\left( {a_{i}b_{i,m}^{H}} \right)}}} \\{\sum\limits_{i = 0}^{L - 1}{\sum\limits_{m = 0}^{M_{i} - 1}{c_{l,{i + L},m}\left( {a_{i}b_{i,m}^{H}} \right)}}}\end{bmatrix}},} & \left( {{Eq}.4} \right)\end{matrix}$

where for a given i, the number of basis vectors is M_(i) and thecorresponding basis vectors are {b_(i,m)}. Note that M_(i) is the numberof coefficients c_(l,i,m) reported by the UE for a given i, whereM_(i)≤M (where {M₁} or ΣM_(i) is either fixed, configured by the gNB orreported by the UE).

The columns of W^(l) are normalized to norm one. For rank R or R layers(υ=R), the pre-coding matrix is given by

$W^{(R)} = {{\frac{1}{\sqrt{R}}\left\lbrack {W^{1}W^{2}\cdots W^{R}} \right\rbrack}.}$

Eq. 2 is assumed in the rest of the disclosure. The embodiments of thedisclosure, however, are general and are also applicable to Eq. 1, Eq. 3and Eq. 4.

L≤2N₁N₂ and K≤N₃. If L=2N₁N₂, then A is an identity matrix, and hencenot reported. Likewise, if K=N₃, then B is an identity matrix, and hencenot reported. Assuming L<2N₁N₂, in an example, to report columns of A,the oversampled DFT codebook is used. For instance, a_(i)=v_(l,m), wherethe quantity v_(l,m) is given by:

$u_{m} = \left\{ {{\begin{matrix}\left\lbrack {1e^{j\frac{2\pi m}{O_{2}N_{2}}}\cdots e^{j\frac{2\pi{m({N_{2} - 1})}}{O_{2}N_{2}}}} \right\rbrack & {N_{2} > 1} \\1 & {N_{2} = 1}\end{matrix}v_{l,m}} = {\left\lbrack {u_{m}e^{j\frac{2\pi l}{O_{1}N_{1}}}u_{m}\cdots e^{j\frac{2\pi{l({N_{1} - 1})}}{O_{1}N_{1}}}u_{m}} \right\rbrack^{T}.}} \right.$

Similarly, assuming K<N₃, in an example, to report columns of B, theoversampled DFT codebook is used. For instance, b_(k)=w_(k), where thequantity w_(k) is given by:

$w_{k} = {\left\lbrack {1e^{j\frac{2\pi k}{O_{3}N_{3}}}\cdots e^{j\frac{2\pi{k({N_{3} - 1})}}{O_{3}N_{3}}}} \right\rbrack.}$

In another example, discrete cosine transform DCT basis is used toconstruct/report basis B for the 3^(rd) dimension. The m-th column ofthe DCT compression matrix is simply given by

$\left\lbrack W_{f} \right\rbrack_{nm} = \left\{ {\begin{matrix}{\frac{1}{\sqrt{K}},{n = 0}} \\{{\sqrt{\frac{2}{K}}\cos\frac{{\pi\left( {{2m} + 1} \right)}n}{2K}},{n = 1},{{\ldots K} - 1}}\end{matrix},,{{{and}K} = N_{3}},{{{and}m} = 0},\ldots,{N_{3} - 1.}} \right.$

Since DCT is applied to real valued coefficients, the DCT is applied tothe real and imaginary components (of the channel or channeleigenvectors) separately. Alternatively, the DCT is applied to themagnitude and phase components (of the channel or channel eigenvectors)separately. The use of DFT or DCT basis is for illustration purposeonly. The disclosure is applicable to any other basis vectors toconstruct/report A and B.

Also, in an alternative, for reciprocity-based Type II CSI reporting, aUE is configured with higher layer parameter CodebookType set to‘TypeII-PortSelection-Compression’ or ‘TypeIII-PortSelection’ for anenhanced Type II CSI reporting with port selection in which thepre-coders for all SBs and for a given layer l=1, . . . , v, where v isthe associated RI value, is given by W^(l)=AC_(l)B^(H), where N₁, N₂,N₃, and c_(l,i,k) are defined as above except that the matrix Acomprises port selection vectors. For instance, the L antenna ports perpolarization or column vectors of A are selected by the index q₁, where

$q_{1} \in \left\{ {0,1,\ldots,{\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil - 1}} \right\}$

(this requires

$\left. {\left\lceil {\log_{2}\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil} \right\rceil{bits}} \right),$

and the value of d is configured with the higher layer parameterPortSelectionSamplingSize, where

$d \in {{\left\{ {1,2,3,4} \right\}{and}d} \leq {{\min\left( {\frac{P_{{CSI} - {RS}}}{2},L} \right)}.}}$

To report columns of A, the port selection vectors are used, Forinstance, a_(i)=v_(m), where the quantity v_(m) is aP_(CSI-RS)/2-element column vector containing a value of 1 in element (mmod P_(CSI-RS)/2) and zeros elsewhere (where the first element iselement 0).

On a high level, a precoder W^(l) can be described as follows.

W ^(l) =AC _(l) B ^(H) =W ₁ {tilde over (W)} ₂ W _(f) ^(H),  (5)

where A=W₁ corresponds to the W₁ in Type II CSI codebook, i.e.,

$W_{1} = {{\begin{bmatrix}A & 0 \\0 & A\end{bmatrix}{and}B} = {W_{f}.}}$

The C={tilde over (W)}₂ matrix consists of all the required linearcombination coefficients (e.g., amplitude and phase or real orimaginary). Each reported coefficient (c_(l,i,m)=p_(l,i,m)ϕ_(l,i,m)) in{tilde over (W)}₂ is quantized as amplitude coefficient (p_(l,i,m)) andphase coefficient (ϕ_(l,i,m)).

In one example, the amplitude coefficient (p_(l,i,m)) is reported usingan A-bit amplitude codebook where A belongs to {2, 3, 4}. If multiplevalues for A are supported, then one value is configured via higherlayer signaling. In another example, the amplitude coefficient(p_(l,i,m)) is reported as p_(l,i,m)=p_(l,i,m) ⁽¹⁾p_(l,i,m) ⁽²⁾ where:

-   -   p_(l,i,m) ⁽¹⁾ is a reference or first amplitude which is        reported using a A1-bit amplitude codebook where A1 belongs to        {2, 3, 4}, and    -   p_(l,i,m) ⁽²⁾ is a differential or second amplitude which is        reported using a A2-bit amplitude codebook where A2≤A1 belongs        to {2, 3, 4}.

For layer l, let us denote the linear combination (LC) coefficientassociated with spatial domain (SD) basis vector (or beam) i∈{0, 1, . .. , 2L_(l)−1} and frequency domain (FD) basis vector (or beam) m∈{0, 1,. . . , M_(l)−1} as c_(l,i,m), and the strongest coefficient asc_(l,i*,m*). Here, (L_(l), M_(l)) denotes the number of SD and FD basisvectors for layer l. In one example, L_(l)=L. The strongest coefficientis reported out of the K_(NZ,l) non-zero (NZ) coefficients that arereported using a bitmap of length 2L_(l)M_(l), whereK_(NZ,l)≤K_(0,l)=┌β_(l)×2L_(l)M_(l)┐<2L_(l)M_(l) and β_(l) is higherlayer configured. In one example, β_(l)=β for rank 1-2. In one example,β_(l) for rank>2 is either fixed (based on β for rank 1-2) or higherlayer configured. The remaining 2L_(l)M_(l)−K_(NZ,l) coefficients thatare not reported by the UE are assumed to be zero.

In one example, the following quantization scheme is used toquantize/report the K_(NZ,l) NZ coefficients for each layer l.

-   -   The UE reports the following for the quantization of the NZ        coefficients in {tilde over (W)}₂:        -   A X_(l)-bit strongest coefficient indicator (SCI_(l)) for            the strongest coefficient index (i*, m*)            -   Strongest coefficient c_(l,i*,m*)=1 (hence its                amplitude/phase are not reported).        -   Two antenna polarization-specific reference amplitudes:            -   For the polarization associated with the strongest                coefficient c_(l,i*,m*)=1, since the reference amplitude                p_(l,i,m) ⁽¹⁾=1, it is not reported.)            -   For the other polarization, reference amplitude                p_(l,i,m) ⁽¹⁾ is quantized to 4 bits                -   The 4-bit amplitude alphabet is

$\left\{ {1,\left( \frac{1}{2} \right)^{\frac{1}{4}},\left( \frac{1}{4} \right)^{\frac{1}{4}},\left( \frac{1}{8} \right)^{\frac{1}{4}},\ldots,\left( \frac{1}{2^{14}} \right)^{\frac{1}{4}},} \right.$

-   -   -   -   -    “reserved”}.

        -   For {c_(l,i,m), (i, m)≠(i*, m*)}:            -   For each polarization, differential amplitudes p_(l,i,m)                ⁽²⁾ of the coefficients calculated relative to the                associated polarization-specific reference amplitude and                quantized to 3 bits.                -   The 3-bit amplitude alphabet is

$\left\{ {1,\frac{1}{\sqrt{2}},\frac{1}{2},\frac{1}{2\sqrt{2}},\frac{1}{4},\frac{1}{4\sqrt{2}},\frac{1}{8},\frac{1}{8\sqrt{2}}} \right\}.$

-   -   -   -   -   Note: The final quantized amplitude p_(l,i,m) is                    given by p_(l,i,m) ⁽¹⁾×p_(l,i,m) ⁽²⁾.

            -   Each phase is quantized to either 8PSK (N_(ph)=8) or                16PSK (N_(ph)=16) (which is configurable).

In the rest of the disclosure, an index m and an index f are usedinterchaeably to indicate an FD/TD index taking a value from {0, 1, . .. , M−1} or {0, 1, . . . , M_(l)−1}. Likewise, c_(l,i,m) and c_(l,i,f)are used interchangeably for a coefficient. Likewise, c_(l,i*,m*) andc_(l,i*,f*) are used interchangeably for a strongest coefficient.

A UE can be configured to report M FD basis vectors. In one example,

${M = \left\lceil {p \times \frac{N_{3}}{R}} \right\rceil},$

where R is higher-layer configured from {1,2} and p is higher-layerconfigured from {¼,½}. In one example, the p value is higher-layerconfigured for rank 1-2 CSI reporting. For rank>2 (e.g., rank 3-4), thep value (denoted by v₀) can be different. In one example, for rank 1-4,(p, v₀) is jointly configured from {(½,¼), (¼,¼), (¼,⅛)}, i.e.

$M = \left\lceil {p \times \frac{N_{3}}{R}} \right\rceil$

for rank 1-2 and

$M = \left\lceil {v_{0} \times \frac{N_{3}}{R}} \right\rceil$

for rank 3-4.

A UE can be configured to report M FD basis vectors in one-step from N₃orthogonal DFT basis vectors freely (independently) for each layer l∈{0,1, . . . , v−1} of a rank v CSI reporting. Alternatively, a UE can beconfigured to report M FD basis vectors in two-step as follows:

-   -   In step 1, an intermediate set (InS) comprising N′₃<N₃ basis        vectors are selected/reported, wherein the InS is common for all        layers.    -   In step 2, for each layer l∈{0, 1, . . . , v−1} of a rank v CSI        reporting, M FD basis vectors are selected/reported freely        (independently) from N′₃ basis vectors in the InS.        In one example, a one-step method is used when N₃≤19 and a        two-step method is used when N₃>19. In one example, N′₃=┌αM┐        where α>1 is configurable.

The codebook parameters used in the DFT based frequency domaincompression (eq. 5) are (L, p, v₀, β, α, N_(ph)). In one example, theset of values for these codebook parameters are as follows:

-   -   L: the set of values is {2,4} in general, except L∈{2,4,6} for        rank 1-2, 32 CSI-RS antenna ports, and R=1.    -   p for rank 1-2, and (p, v₀) for rank 3-4: p∈{¼,½} and (p,        v₀)∈{(½,¼), (¼,¼), (¼,⅛)}.    -   β∈{¼,½,¾}.    -   α∈{1.5,2,2.5,3}    -   N_(ph)∈{8,16}.

This disclosure extends the DFT-based (frequency domain) compressionaccording to the framework in equation (5) to spatial domain portselection. In particular, a UE is configured with higher layer parameterCodebookType set to ‘TypeII-PortSelection-Compression’ or‘TypeIII-PortSelection’ for an enhanced Type II CSI reporting with portselection in which the pre-coders for all SBs and for a given layer l=1,. . . , v, where v is the associated RI value, is given byW^(l)=AC_(l)B^(H), where N₁, N₂, N₃, and c_(l,i,k) are defined as aboveexcept that the matrix A comprises port selection vectors to selection Lantenna ports. In one example, this port selection is common for the twoantenna polarizations. The rest of the disclosure proposes severalembodiments for rank 1-4 CSI reporting according to this extension toport selection.

In embodiment 1, for rank 1-2 CSI reporting, the value of L isconfigured with the higher layer parameter numberOfBeams, where L=2 whenP_(CSI-RS)=4 and L∈{2,3,4} when P_(CSI-RS)>4. Alternatively, the valueof L is configured with the higher layer parameter numberOfBeams, whereL=2 when P_(CSI-RS)=4 and L∈{2,4} when P_(CSI-RS)>4. Alternatively, thevalue of L is configured with the higher layer parameter numberOfBeams,where L=2 when P_(CSI-RS)=4, L∈{2,4} when P_(CSI-RS)>4 andP_(CSI-RS)≠32, and L∈{2,4,6} when P_(CSI-RS)=32.

For rank 3-4 CSI reporting, the value of L is configured with the higherlayer parameter numberOfBeams, where L=2 when P_(CSI-RS)=4 and L∈{2,3,4}when P_(CSI-RS)>4. Alternatively, the value of L is configured with thehigher layer parameter numberOfBeams, where L=2 when P_(CSI-RS)=4 andL∈{2,4} when P_(CSI-RS)>4.

In embodiment 2, for rank 1-2 CSI reporting, the L antenna ports perpolarization or column vectors of A are selected by the index q₁, where

$q_{1} \in \left\{ {0,1,\ldots,{\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil - 1}} \right\}$

(this requires

$\left. {\left\lceil {\log_{2}\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil} \right\rceil{bits}} \right),$

and the value of d is configured with the higher layer parameterPortSelectionSamplingSize, where d∈{1,2,3,4} and

$d \leq {{\min\left( {\frac{P_{{CSI} - {RS}}}{2},L} \right)}.}$

In one example, the index q₁ is reported via PMI index i_(1,1). Toreport columns of A, the port selection vectors are used, For instance,a_(i)=v_(m), where the quantity v_(m) is a P_(CSI-RS)/2-element columnvector containing a value of 1 in element (m mod P_(CSI-RS)/2) and zeroselsewhere (where the first element is element 0). Note that for rank 2,the L antenna port selection vectors are layer-common, i.e., they arecommon for the two layers 0-1 of rank 2 CSI reporting. The portselection matrix is given by

$\begin{matrix}{W_{1} = {{\begin{bmatrix}X & 0 \\0 & X\end{bmatrix}{where}X} = {\left\lbrack {v_{i_{1,1}d}v_{{i_{1,1}d} + 1}\cdots v_{{i_{1,1}d} + L - 1}} \right\rbrack.}}} & (6)\end{matrix}$

In embodiment 3, for rank v∈{3,4} CSI reporting, the L antenna ports perpolarization or column vectors of A are selected as follows. For layers0 and 1, the L antenna ports per polarization or column vectors of A areselected, similar to embodiment 2, by the index q₁, where

$q_{1} \in \left\{ {0,1,\ldots,{\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil - 1}} \right\}$

(this requires

$\left. {\left\lceil {\log_{2}\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil} \right\rceil{bits}} \right),$

and the value of d is configured with the higher layer parameterPortSelectionSamplingSize, where d∈{1,2,3,4} and

$d \leq {{\min\left( {\frac{P_{{CSI} - {RS}}}{2},L} \right)}.}$

In one example, the index q₁ is reported via PMI index i_(1,1). Toreport columns of A, the port selection vectors are used, For instance,a_(i)=v_(m), where the quantity v_(m) is a P_(CSI-RS)/2-element columnvector containing a value of 1 in element (m mod P_(CSI-RS)/2) and zeroselsewhere (where the first element is element 0).

For layer 2 and v−1, the L antenna ports per polarization or columnvectors of A are selected according to at least one of the followingalternatives (Alt).

In one alternative Alt 3-0, the value of L and d are configured commonfor all layers, i.e., they are the same for both layer pair (0, 1) andlayer pair (2, 3). The port selection matrix W₁ is according to at leastone of the following sub-alternatives.

In one alternative Alt 3-0-0, the port selection matrix W₁ is common(hence, remains the same) for all layers regardless of the rank value.The PMI i1,1 indicates this common W₁ for all layers.

In one alternative Alt 3-0-1, the port selection matrix W₁ is layer-paircommon, i.e., one W_(1,1) for layer pair (0, 1) and another W_(1,2) forlayer pair (2, 3), where W_(1,1) can be different from W_(1,1). In thiscase, the PMI i1,1 indicates W_(1,1) for layer 0-1 (same as Rel. 15),and a separate PMI, e.g., i1,2, indicates W_(1,2) for layer 2-3, wherefor k∈{0,1}, we have

$W_{1,k} = {{\begin{bmatrix}X_{k} & 0 \\0 & X_{k}\end{bmatrix}{and}X_{k}} = {\left\lbrack {v_{i_{1,k}d}v_{{i_{1,k}d} + 1}\cdots v_{{i_{1,k}d} + L - 1}} \right\rbrack.}}$

Alternatively, i1,1 indicates both W_(1,1) and W_(1,2) jointly.Alternatively, i_(1,1)=[i_(1,1,1) i_(1,1,2)] where i_(1,1,k) indicatesW_(1,k).

In one example, the port selection matrix W₁ is according to Alt 3-0-1when L=2 and is according to Alt 3-0-0 when L>2, for example, when L=4.

In one alternative Alt 3-1, the value of L is configured common for alllayers, i.e., they are the same for both layer pair (0, 1) and layerpair (2, 3), but the value of d is configured common for layer pair(0, 1) and another value d₂ is used for layer pair (2, 3). Let us defined₁=d. The port selection matrix W₁ is layer-pair common, i.e., oneW_(1,1) for layer pair (0, 1) and another W_(1,2) for layer pair (2, 3),where W_(1,1) is different from W_(1,1). In this case, the PMI i1,1indicates W_(1,1) for layer 0-1 (same as Rel. 15), and a separate PMI,e.g., i1,2, indicates W_(1,2) for layer 2-3, where for k∈{0,1}, we have

$W_{1,k} = {{\begin{bmatrix}X_{k} & 0 \\0 & X_{k}\end{bmatrix}{and}X_{k}} = {\left\lbrack {v_{i_{1,k}d}v_{{i_{1,k}d} + 1}\cdots v_{{i_{1,k}d} + L - 1}} \right\rbrack.}}$

Alternatively, i1,1 indicates both W_(1,1) and W_(1,2) jointly.Alternatively, i_(1,1)=[i_(1,1,1) i_(1,1,2)] where i_(1,1,k) indicatesW_(1,k). The (d₁, d₂) is determined according to at least one of thefollowing alternatives.

In one alternative Alt 3-1-0: the value of d₁ is configured the same wayas in Rel. 15 (i.e., via higher layer signaling), and the value of d₂ isdetermined based on the configured value of d₁. For example, d₂=max(1,d₁−1).

In one alternative Alt 3-1-1: both d₁ and d₂ are configured, e.g., viahigher layer signaling, either jointly using a single parameter orseparately using two separate parameters.

In one alternative Alt 3-1-2: the value of d₂ is reported by the UE.This report can be either jointly using an existing CSI parameter (e.g.,PMI) or separately using a new separate CSI parameter.

In one alternative In Alt 3-2, the value of d is configured common forall layers, i.e., they are the same for both layer pair (0, 1) and layerpair (2, 3), but the value of L is configured common for layer pair(0, 1) and another value L₂ is used for layer pair (2, 3). Let us defineL₁=L. The port selection matrix W₁ is layer-pair common, i.e., oneW_(1,1) for layer pair (0, 1) and another W_(1,2) for layer pair (2, 3),where W_(1,1) is different from W_(1,1). In this case, the PMI i1,1indicates W_(1,1) for layer 0-1 (same as Rel. 15), and a separate PMI,e.g., i1,2, indicates W_(1,2) for layer 2-3, where for k∈{0,1}, we have

$W_{1,k} = {{\begin{bmatrix}X_{k} & 0 \\0 & X_{k}\end{bmatrix}{and}X_{k}} = {\left\lbrack {v_{i_{1,k}d}v_{{i_{1,k}d} + 1}\cdots v_{{i_{1,k}d} + L - 1}} \right\rbrack.}}$

Alternatively, i1,1 indicates both W_(1,1) and W_(1,2) jointly.Alternatively, i_(1,1)=[i_(1,1,1) i_(1,1,2)] where i_(1,1,k) indicatesW_(1,k). The (L₁, L₂) is determined according to at least one of thefollowing alternatives.

In one alternative Alt 3-2-0: the value of L₁ is configured the same wayas in Rel. 15 (i.e., via higher layer signaling), and the value of L₂ isdetermined based on the configured value of L₁. For example, L₂=max(1,L₁−1).

In one alternative Alt 3-2-1: both L₁ and L₂ are configured, e.g., viahigher layer signaling, either jointly using a single parameter orseparately using two separate parameters.

In one alternative Alt 3-2-2: the value of L₂ is reported by the UE.This report can be either jointly using an existing CSI parameter (e.g.,PMI) or separately using a new separate CSI parameter.

In embodiment 4, for rank v∈{3,4} CSI reporting, the parameters L₁ andd₁ are used for layer pair (0, 1) and parameters L₂ and d₂ are used forlayer pair (2, 3). For k∈{0,1}, the L_(k) antenna ports per polarizationor column vectors of A are selected, similar to embodiment 2, by theindex q_(1,k), where

$q_{1,k} \in \left\{ {0,1,\ldots,{\left\lceil \frac{P_{{CSI} - {RS}}}{2d_{k}} \right\rceil - 1}} \right\}$

(this requires

$\left. {\left\lceil {\log_{2}\left\lceil \frac{P_{{CSI} - {RS}}}{2d_{k}} \right\rceil} \right\rceil{bits}} \right).$

The index q₁=[q_(1,1) q_(1,2)] is reported either jointly or separately.

At least one of the following alternatives is used for (d₁, d₂).

In one alternative Alt 4-0, the value of d is configured, e.g., viahigher layer parameter PortSelectionSamplingSize, and d₁ and d₂ arederived based on the configured value of d. At least one of thefollowing examples is used.

In one example Ex 4-0-0:

${d_{1} = \left\lceil \frac{d}{2} \right\rceil},{d_{2} = {{\max\left( {d - \left\lceil \frac{d}{2} \right\rceil} \right)}{or}{\max\left( {1,\left\lfloor \frac{d}{2} \right\rfloor} \right)}}}$

In one example Ex 4-0-1:

${d_{1} = {\max\left( {1,\left\lfloor \frac{d}{2} \right\rfloor} \right)}},{d_{2} = {{\max\left( {d - \left\lfloor \frac{d}{2} \right\rfloor} \right)}{or}\left\lceil \frac{d}{2} \right\rceil}}$

In one example Ex 4-0-2: d₂=2, d₁=max(1, d−d₂)

In one example Ex 4-0-3: d₂=1, d₁=max(1, d−d₂)

In one alternative Alt 4-1, the value of d and d₁ are configured, e.g.,via higher layer parameter PortSelectionSamplingSize andPortSelectionSamplingSize-d1, respectively, and d₂ is derived based onthe configured value of d and d₁. The value of d₂ is fixed, e.g., tod₂=max(1, d−d₁).

In one alternative Alt 4-2, the value of d and d₂ are configured, e.g.,via higher layer parameter PortSelectionSamplingSize andPortSelectionSamplingSize-d2, respectively, and d₁ is derived based onthe configured value of d and d₂. The value of d₁ is fixed, e.g., tod₁=max(1, d−d₂).

In one alternative Alt 4-3, the value of d₁ and d₂ are configured, e.g.,via higher layer parameter PortSelectionSamplingSize-d1 andPortSelectionSamplingSize-d2, respectively.

At least one of the following alternatives is used for (L₁, L₂).

In one alternative Alt 4-4, the value of L is configured, e.g., viahigher layer parameter numberOfBeams, and L₁ and L₂ are derived based onthe configured value of L. At least one of the following examples isused.

In one example Ex 4-4-0:

${L_{1} = \left\lceil \frac{L}{2} \right\rceil},{L_{2} = {L - {L_{1}{or}{\left\lfloor \frac{L}{2} \right\rfloor.}}}}$

In one example Ex 4-4-1:

${L_{2} = \left\lceil \frac{L}{2} \right\rceil},{L_{1} = {L - {L_{2}{or}{\left\lfloor \frac{L}{2} \right\rfloor.}}}}$

In one example Ex 4-4-2: L₂=2, L₁=max(2, L−L₂).

In one example Ex 4-4-3: L₂=1, L₁=max(1, L−L₂).

In one alternative Alt 4-5, the value of L and L₁ are configured, e.g.,via higher layer parameter numberOfBeams and numberOfBeams-L1,respectively, and L₂ is derived based on the configured value of L andL₁. The value of L₂ is fixed, e.g., to L₂=L−L₁.

In one alternative Alt 4-6, the value of L and L₂ are configured, e.g.,via higher layer parameter numberOfBeams and numberOfBeams-L2,respectively, and L₁ is derived based on the configured value of L andL₂. The value of L₁ is fixed, e.g., to L₁=L−L₂.

In one alternative Alt 4-7, the value of L₁ and L₂ are configured, e.g.,via higher layer parameter numberOfBeams-L1 and numberOfBeams-L2,respectively.

In embodiment 5, the rank v∈{3,4} CSI reporting is supported based on acertain condition.

In one example Ex 5-0: the condition is based on the value of L, forexample, the value of L is fixed to 4.

In one example Ex 5-1: the condition is based on the value of d, forexample, the value of d is restricted to 4 or a value from {3, 4}.

In one example Ex 5-2: the condition is based on the number of ports,P_(CSI-RS), for example, the rank 3-4 port selection is supported onlyP_(CSI-RS)>x, where x is fixed, e.g., to x=4 or 8 or 16.

In one example Ex 5-3: the condition is based on a combination of L, d,or/and P_(CSI-RS).

In another example, the set of values for the codebook parameters (L, p,v₀, β, α, N_(ph)) are as follows: α=2, N_(ph)=16, and

p = y₀ p = v₀ Restriction (if L (RI = 1-2) (RI = 3-4) β any) 2 ¼ ⅛ ¼ 2 ¼⅛ ½ 4 ¼ ⅛ ¼ 4 ¼ ⅛ ½ 4 ½ ¼ ½ 6 ¼ — ½ RI = 1-2, 32 ports 4 ¼ ¼ ¾ 6 ¼ — ¾RI = 1-2, 32 ports

The above-mentioned framework (equation 5) represents theprecoding-matrices for multiple (N₃) FD units using a linear combination(double sum) over 2L SD beams and M FD beams. This framework can also beused to represent the precoding-matrices in time domain (TD) byreplacing the FD basis matrix W_(f) with a TD basis matrix W_(t),wherein the columns of W_(t) comprises M TD beams that represent someform of delays or channel tap locations. Hence, a precoder W^(l) can bedescribed as follows.

W=A _(l) C _(l) B _(l) ^(H) =W ₁ {tilde over (W)} ₂ W _(t) ^(H).  (5A)

In one example, the M TD beams (representing delays or channel taplocations) are selected from a set of N₃ TD beams, i.e., N₃ correspondsto the maximum number of TD units, where each TD unit corresponds to adelay or channel tap location. In one example, a TD beam corresponds toa single delay or channel tap location. In another example, a TD beamcorresponds to multiple delays or channel tap locations. In anotherexample, a TD beam corresponds to a combination of multiple delays orchannel tap locations.

The rest of disclosure is applicable to both space-frequency (equation5) and space-time (equation 5A) frameworks.

In general, for layer l=0,1, . . . , v−1, where v is the rank valuereported via RI, the pre-coder (cf. equation 5 and equation 5A) includesthe codebook components summarized in Table 1 (when a strongestcoefficient is not included in the codebook) and in Table 2 (when astrongest coefficient is included in the codebook).

TABLE 1 Codebook Components Index Components Description 0 L_(l) numberof SD beams 1 M_(l) number of FD/TD beams 2 {a_(l,i)}_(i=0) ^(L) ^(l) ⁻¹set of SD beams comprising columns of A_(l) 3 {b_(l,m)}_(m=0) ^(M) ^(l)⁻¹ set of FD/TD beams comprising columns of B_(l) 4 {x_(l,i,m)} bitmapindicating the indices of the non-zero (NZ) coefficients 5 {p_(l,i,m)}amplitudes of NZ coefficients indicated via the bitmap 6 {ϕ_(l,i,m)}phases of NZ coefficients indicated via the bitmap

TABLE 2 Codebook Components Index Components Description 0{a_(l,i)}_(i=0) ^(L) ^(l) ⁻¹ set of SD beams comprising columns of A_(l)1 {b_(l,m)}_(m=0) ^(M) ^(l) ⁻¹ set of FD/TD beams comprising columns ofB_(l) 2 (i*, m*) an index of a strongest coefficient c_(l,i*,m*) 3{x_(l,i,m)} bitmap indicating the indices of the non-zero (NZ)coefficients 4 {p_(l,i,m)} amplitudes of NZ coefficients indicated viathe bitmap 5 {ϕ_(l,i,m)} phases of NZ coefficients indicated via thebitmap

In one example, the number of SD beams is layer-common, i.e., L_(l)=Lfor all l values. In one example, the set of SD basis is layer-common,i.e., a_(l,i)=a_(i) for all l values. In one example, the number ofFD/TD beams is layer-pair-common or layer-pair-independent, i.e.,M₀=M₁=M for layer pair (0, 1), M₂=M₃=M′ for layer pair (2, 3), and M andM′ can have different values. In one example, the set of FD/TD basis islayer-independent, i.e., {b_(l,m)} can be different for different lvalues. In one example, the bitmap is layer-independent, i.e.,{β_(l,i,m)} can be different for different l values. In one example, thecoefficients are layer-independent, i.e., {c_(l,i,m)=p_(l,i,m)ϕ_(l,i,m)}can be different for different l values.

In one example, when the SD basis W₁ is a port selection, then thecandidate values for L or L_(l) include 1, and the candidate values forthe number of CSI-RS ports N CSI-RS include 2.

This disclosure extends the DFT-based (frequency domain) compressionaccording to the framework in equation (5 or 5A) to SD port selectionand/or FD/TD port selection. In one example, for the SD port selection,A_(l) comprises selection vectors to select L antenna ports (out ofP_(CSIRS) CSI-RS antenna ports), where this selection can be common forthe two antenna polarizations or different for the two antennapolarizations. In one example, for the FD/TD port selection, B_(l)comprises selection vectors to select M FD/TD units (out of N₃ FD/TDunits).

In embodiment 6, a UE is configured with a subset (S1) of the codebookcomponents (either via higher layer RRC signaling or MAC CE basedsignaling or DCI based signaling). The UE uses the subset (S1) ofcodebook components and derives a remaining subset (S2) of codebookcomponents (that are not configured to the UE). The UE reports a CSIreport including the remaining subset (S2) of codebook components. Inone example, the subset (S1) of the codebook components is obtainedbased on the UL channel estimated using SRS transmission from the UE.The subset S1 of codebook components (configured to the UE) is accordingto at least one of the following alternatives (Alt) wherein the codebookcomponent indices are as in Table 1.

In one alternative Alt 6-1: the subset S1 includes five codebookcomponents corresponding to indices 0-4

In one alternative Alt 6-2: the subset S1 includes three codebookcomponents corresponding to indices {0, 2, 4}

In one alternative Alt 6-3: the subset S1 includes three codebookcomponents corresponding to indices {1, 3, 4}

In one alternative Alt 6-4: the subset S1 includes four codebookcomponents corresponding to indices 0-3

In one alternative Alt 6-5: the subset S1 includes three codebookcomponents corresponding to indices 2-4

In one alternative Alt 6-6: the subset S1 includes two codebookcomponents corresponding to indices {0, 2}

In one alternative Alt 6-7: the subset S1 includes two codebookcomponents corresponding to indices {1, 3}

In one alternative Alt 6-8: the subset S1 includes two codebookcomponents corresponding to indices {2, 3}

In one alternative Alt 6-9: the subset S1 includes two codebookcomponents corresponding to indices {3, 4}

In one alternative Alt 6-10: the subset S1 includes one codebookcomponent corresponding to index 3.

In one example, all of the remaining subset (S2) of codebook components(that are not configured to the UE) are reported by the UE. For example,when the subset S1 is according to Alt 6-1, then the remaining subset S2comprises a codebook component, corresponding to index 5, is reported bythe UE.

In another example, the remaining subset (S2) of codebook components(that are not configured to the UE) is partitioned into two subsets (S21and S22), the subset (S21) is reported by the UE and the subset (S22) isfixed. For example, when the subset S1 is according to Alt 6-3, then theremaining subset S2 comprises codebook components, corresponding toindices {0, 2, 5}, and the subset S21 can comprise index {5} and S22 cancomprise indices {0, 2}.

In another example, when the subset S1 includes SD basis but not FD/TDbasis, then it also includes power level for each of SD beams includedin this SD basis. Likewise, when the subset S1 includes FD/TD basis butnot SD basis, then it also includes power level for each of FD/TD beamsincluded in this FD/TD basis. When the subset S1 includes both SD basisand FD/TD basis, then it either includes separate power levels for SDand FD bases, i.e., SD power level for each of SD beams included in thisSD basis and FD/TD power level for each of FD/TD beams included in thisFD/TD basis, or includes a joint power level for all combinations of SDand FD/TD beam combinations. Note that in case of separate power level,the total number of power levels is 2L_(l)+M_(l) and in case of jointpower level, the total number of power levels is 2L_(l)M_(l).

In embodiment 6A, a variation of embodiment 6, the subset (S1) of thecodebook components is reported by the UE in a previous CSI report(e.g., the last reported CSI including the subset S1 of codebookcomponents).

In embodiment 6B, a variation of embodiment 6, the subset (S1) of thecodebook components is fixed (hence, neither configured to the UE norreported by the UE). In this variation, the codebook components in setS1 can be obtained by the gNB (NW) based on the UL channel estimatedusing SRS transmission from the UE. Likewise, the codebook components inset S1 can be obtained by the UE based on the DL channel estimated usingCSI-RS transmission from the gNB. If the codebook components in set S1are reciprocal between DL and UL channel estimates, then thesecomponents need not be reported by the UE (to the gNB) or configured tothe UE (by the gNB) since they can be obtained using SRS or CSI-RStransmissions.

In embodiment 7, for SD basis, the set of SD beams {a_(l,i)}_(i=0) ^(L)^(l) ⁻¹ comprising columns of A_(l) is according to at least one of thefollowing alternatives. The SD basis is common for the two antennapolarizations, i.e., one SD basis is used for both antennapolarizations.

In one alternative Alt 7-1, the SD basis is analogous to the W₁component in Rel.15 Type II port selection codebook, wherein the L_(l)antenna ports or column vectors of A_(l) are selected by the index

$q_{1,k} \in \left\{ {0,1,\ldots,{\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil - 1}} \right\}$

(this requires

$\left. {\left\lceil {\log_{2}\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil} \right\rceil{bits}} \right),$

where

$d \leq {\left( {\frac{P_{{CSI} - {RS}}}{2},L_{l}} \right).}$

In one example, d∈{1,2,3,4}. To select columns of A_(l), the portselection vectors are used, For instance, a_(i)=v_(m), where thequantity v_(m) is a P_(CSI-RS)/2-element column vector containing avalue of 1 in element (m mod P_(CSI-RS)/2) and zeros elsewhere (wherethe first element is element 0). The port selection matrix is then givenby

$W_{1} = {A_{l} = {{\begin{bmatrix}X & 0 \\0 & X\end{bmatrix}{where}X} = {\left\lbrack {v_{q_{1}d}v_{{q_{1}d} + 1}\cdots v_{{q_{1}d} + L_{l} - 1}} \right\rbrack.}}}$

In one alternative Alt 7-2, the SD basis selects L_(l) antenna portsfreely, i.e., the L_(l) antenna ports per polarization or column vectorsof A_(l) are selected freely by the index

$q_{1} \in \left\{ {0,1,\ldots,{\begin{pmatrix}\frac{P_{{CSI} - {RS}}}{2} \\L_{l}\end{pmatrix} - 1}} \right\}$

(this requires

$\left. {\left\lceil {\log_{2}\begin{pmatrix}\frac{P_{{CSI} - {RS}}}{2} \\L_{l}\end{pmatrix}} \right\rceil{bits}} \right).$

To select columns of A_(l), the port selection vectors are used, Forinstance, a_(i)=v_(m), where the quantity v_(m) is a -element columnvector containing a value of 1 in element (m mod P_(CSI-RS)/2) and zeroselsewhere (where the first element is element 0). Let {x₀, x₁, . . . ,x_(L) _(l) ⁻¹} be indices of selection vectors selected by the index q₁.The port selection matrix is then given by

$W_{1} = {A_{l} = {{\begin{bmatrix}X & 0 \\0 & X\end{bmatrix}{where}X} = {\left\lbrack {v_{x_{0}}v_{x_{1}\cdots v_{x_{L_{l} - 1}}}} \right\rbrack.}}}$

In one alternative Alt 7-3, the SD basis selects L_(l) DFT beams from anoversampled DFT codebook, i.e., a_(i)=v_(i) ₁ _(,i) ₂ , where thequantity v_(i) ₁ _(,i) ₂ is given by

$u_{i_{2}} = \left\{ {{\begin{matrix}\left\lbrack {1e^{j\frac{2\pi m}{O_{2}N_{2}}}\cdots e^{j\frac{2\pi{m({N_{2} - 1})}}{O_{2}N_{2}}}} \right\rbrack & {N_{2} > 1} \\1 & {N_{1} = 1}\end{matrix}v_{i_{1},i_{2}}} = {\left\lbrack {u_{i_{2}}e^{j\frac{2\pi i_{1}}{O_{1}N_{2}}}u_{i_{2}}\cdots e^{j\frac{2\pi{i_{1}({N_{1} - 1})}}{O_{1}N_{1}}}u_{i_{2}}} \right\rbrack^{T}.}} \right.$

In one example, this selection of L_(l) DFT beams is from a set oforthogonal DFT beams comprising N₁N₂ two-dimensional DFT beams.

In embodiment 7A, a variation of embodiment 2, the SD basis is selectedindependently for each of the two antenna polarizations, according to atleast one of Alt 7-1 through Alt 7-3.

In embodiment 8, for FD/TD basis, the set of FD/TD beams {b_(l,m)}_(m=0)^(M) ^(l) ⁻¹ comprising columns of B_(l) is according to at least one ofthe following alternatives.

In one alternative Alt 8-1, the FD/TD basis selection to similar to Alt7-1, i.e., the M_(l) FD/TD units ports or column vectors of B_(l) areselected by the index

$q_{2} \in \left\{ {0,1,\ldots,{\left\lceil \frac{N_{3}}{e} \right\rceil - 1}} \right\}$

(this requires

$\left. {\left\lceil {\log_{2}\left\lceil \frac{N_{3}}{e} \right\rceil} \right\rceil{bits}} \right),$

where e≤min(N₃, M_(l)). In one example, e∈{1,2,3,4}. To select columnsof B_(l), the selection vectors are used, For instance, b_(m)=v_(z),where the quantity v_(z) is a N₃-element column vector containing avalue of 1 in element (z mod N₃) and zeros elsewhere (where the firstelement is element 0). The selection matrix is then given by

W _(f) =B _(l) =[v _(q) ₂ _(e) v _(q) ₂ _(e+1) . . . v _(q) ₂ _(e+M)_(l) ⁻¹].

In one alternative Alt 8-2, the FD/TD basis selects M_(l) FD/TD unitsfreely, i.e., the M_(l) FD/TD units or column vectors of B_(l) areselected freely by the index

$q_{2} \in \left\{ {0,1,\ldots,{\begin{pmatrix}N_{3} \\M_{l}\end{pmatrix} - 1}} \right\}$

(this requires

$\left. {\left\lceil {\log_{2}\begin{pmatrix}N_{3} \\M_{l}\end{pmatrix}} \right\rceil{bits}} \right).$

To select columns of B_(l), the selection vectors are used, Forinstance, b_(m)=v_(z), where the quantity v_(z) is a N₃-element columnvector containing a value of 1 in element (z mod N₃) and zeros elsewhere(where the first element is element 0). Let {x₀, x₁, . . . , x_(M) _(l)⁻¹} be indices of selection vectors selected by the index q₂. Theselection matrix is then given by

W _(f) =B _(l) =[v _(x) ₀ v _(x) ₁ . . . v _(x) _(Ml−1) ].

In one alternative Alt 8-3, the FD/TD basis selects M_(l) DFT beams froman oversampled DFT codebook, i.e., b_(k)=W_(k), where the quantity w_(k)is given by

$w_{k} = {\left\lbrack {1e^{j\frac{2\pi k}{O_{3}N_{3}}}\cdots e^{j\frac{2\pi{k({N_{3} - 1})}}{O_{3}N_{3}}}} \right\rbrack.}$

In one example, this selection of M_(l) DFT beams is from a set oforthogonal DFT beams comprising N₃ DFT beams. In one example, O₃=1.

In embodiment 9, the SD and FD/TD basis is according to at least one ofthe alternatives in Table 3.

TABLE 3 Alternatives for SD and FD/TD Bases Alt SD basis FD/TD basis 9-0Alt 7-1 Alt 8-1 9-1 Alt 8-2 9-2 Alt 8-3 9-3 Alt 7-2 Alt 8-1 9-4 Alt 8-29-5 Alt 8-3 9-6 Alt 7-3 Alt 8-1 9-7 Alt 8-2 9-8 Alt 8-3

In embodiment 10, when the FD/TD basis comprising N′₃ FD/TD beams isconfigured to the UE (cf. embodiment 6), then the FD/TD basis selectionis according to at least one of the following alternatives.

In one alternative Alt 10-1: when N′₃=M_(l), the UE uses the configuredFD/TD basis for all layers to determine the rest of the codebookcomponents.

In one alternative Alt 10-2: when N′₃>M_(l), the UE uses the configuredFD/TD basis as an intermediate basis, common for all layers, and selectsM_(l) out of N′₃ bases independently for each layer. The UE reports theselected M_(l) FD/TD bases in the CSI report together with the othercodebook components.

In embodiment 11, when the bitmap indicating X NZ indices is configuredto the UE (cf. embodiment 6), then the bitmap selection is according toat least one of the following alternatives.

In one alternative Alt 11-1: when a certain condition is met (e.g., X=t,a threshold value), the UE uses the configured bitmap for all layers todetermine the rest of the codebook components.

In one alternative Alt 11-2: when a certain condition is met (e.g., X>t,a threshold value), the UE uses the configured bitmap as an intermediatebasis, common for all layers, and selects bitmaps independently for eachlayer such that the selected NZ coefficients are included in theconfigured bitmap. The UE reports the selected bitmap in the CSI reporttogether with the other codebook components.

FIG. 14 illustrates a flow chart of a method 1400 for operating a userequipment (UE) for channel state information (CSI) reporting in awireless communication system, as may be performed by a UE such as UE116, according to embodiments of the present disclosure. The embodimentof the method 1400 illustrated in FIG. 14 is for illustration only. FIG.13 does not limit the scope of this disclosure to any particularimplementation.

As illustrated in FIG. 14 , the method 1400 begins at step 1402. In step1402, the UE (e.g., 111-116 as illustrated in FIG. 1 ) receivesconfiguration information for a CSI report. The configurationinformation includes information to: configure a codebook and parametersfor the codebook, the codebook comprising a precoding matrix indicator(PMI) indicating a set of components S to represent N₃ precodingmatrices, where N₃≥1; and partition the PMI into two subsets, a firstPMI subset indicating a first subset of components S1 from the set ofcomponents S, and a second PMI subset indicating a second subset ofcomponents S2 from the set of components S different from the firstsubset of components S1.

In step 1404, the UE determines the CSI report based on theconfiguration information, the CSI report including the second PMIsubset indicating the second subset of components S2.

In step 1406, the UE transmits the determined CSI report over an uplink(UL) channel.

In one embodiment, the UE receives first PMI subset indicating the firstsubset of components S1 via higher layer signaling.

In one embodiment, in a prior time slot, the UE determines another CSIreport that includes the first PMI subset indicating the first subset ofcomponents S1; and transmits the another CSI report in the prior timeslot.

In one embodiment, each of the N₃ precoding matrices has v columns andan l-th column of the N₃ precoding matrices are represented by columnsof

${W^{l} = {{{\frac{1}{\sqrt{v}}\begin{bmatrix}A & 0 \\0 & A\end{bmatrix}}C_{l}B_{l}^{H}} = \begin{bmatrix}{\sum\limits_{f = 0}^{M - 1}{\sum\limits_{i = 0}^{L - 1}{c_{l,i,f}\left( {a_{i}b_{l,f}^{H}} \right)}}} \\{\sum\limits_{f = 0}^{M - 1}{\sum\limits_{i = 0}^{L - 1}{c_{l,{i + L},f}\left( {a_{i}b_{l,f}^{H}} \right)}}}\end{bmatrix}}},{{{where}l} \in {{\left\{ {1,\ldots,v} \right\}{and}v} \geq 1}}$

is a rank value, A=[a₀ a₁ . . . a_(L-1)], a_(i) is a

$\frac{P}{2} \times 1$

column vector whose one entry is 1 and remaining entries are 0, and P isa number of antenna ports in spatial domain (SD), B_(l)=[b_(l,0) b_(l,1). . . b_(l,M-1)], b_(l,f) is a Q×1 column vector, and Q is a number ofantenna ports in frequency domain (FD), C_(l) is a 2L×M matrixcomprising coefficients c_(l,i,f) with row index i∈{0, 1, . . . , 2L−1}and column index f∈{0, 1, . . . , M−1}; and the set of components Scomprises: Component 1: {a_(i)}_(i=0) ^(L-1) indicating L SD portselection vectors, and for each l∈{1, . . . , v}, Component 2:{b_(l,f)}_(f=0) ^(M-1) indicating M FD basis vectors, Component 3: Index(i*, f*) indicating an index of a strongest coefficient c_(l,i*f*),Component 4: Bitmap {x_(l,i,f)} indicating indices of non-zero (NZ)coefficients of C_(l), Component 5: Amplitudes {p_(l,i,f)} of the NZcoefficients of C₁, and Component 6: Phases {ϕ_(l,i,f)} of the NZcoefficients of C_(l).

In one embodiment, the first subset of components S1 includes Component2 and the second subset of components S2 includes Components 1, 3, 4, 5,and 6.

In one embodiment, the first subset of components S1 includes Components1 and 2 and the second subset of components S2 includes Components 3, 4,5, and 6.

In one embodiment, b_(l,f) is a FD port selection vector whose one entryis 1 and remaining entries are 0.

In one embodiment, L SD vectors are selected freely from

$\frac{P}{2}$

candidate SD vectors, and the selected vectors are reported via a

$\left\lceil {\log_{2}\begin{pmatrix}\frac{P}{2} \\L\end{pmatrix}} \right\rceil$

-bit indicator included in the CSI report.

FIG. 15 illustrates a flow chart of another method 1500, as may beperformed by a base station (BS) such as BS 102, according toembodiments of the present disclosure. The embodiment of the method 1500illustrated in FIG. 15 is for illustration only. FIG. 15 does not limitthe scope of this disclosure to any particular implementation.

As illustrated in FIG. 15 , the method 1500 begins at step 1502. In step1502, the BS (e.g., 101-103 as illustrated in FIG. 1 ), generates CSIfeedback configuration information for a CSI report. The configurationinformation includes information to: configure a codebook and parametersfor the codebook, the codebook comprising a precoding matrix indicator(PMI) indicating a set of components S to represent N₃ precodingmatrices, where N₃≥1; and partition the PMI into two subsets, a firstPMI subset indicating a first subset of components S1 from the set ofcomponents S, and a second PMI subset indicating a second subset ofcomponents S2 from the set of components S different from the firstsubset of components S1.

In step 1504, the BS transmits the CSI feedback configurationinformation for the CSI report.

In step 1506, the BS receives the CSI report over an uplink (UL)channel, the CSI report including the second PMI subset indicating thesecond subset of components S2.

In one embodiment, the BS determines the first PMI subset indicating thefirst subset of components S1; and transmits the first PMI subsetindicating the first subset of components S1 via higher layer signaling.

In one embodiment the first PMI subset indicating the first subset ofcomponents S1 is received via another CSI report in a prior time slot.

In one embodiment, each of the N₃ precoding matrices has v columns andan l-th column of the N₃ precoding matrices are represented by columnsof

${W^{l} = {{{\frac{1}{\sqrt{v}}\begin{bmatrix}A & 0 \\0 & A\end{bmatrix}}C_{l}B_{l}^{H}} = \begin{bmatrix}{\sum\limits_{f = 0}^{M - 1}{\sum\limits_{i = 0}^{L - 1}{c_{l,i,f}\left( {a_{i}b_{l,f}^{H}} \right)}}} \\{\sum\limits_{f = 0}^{M - 1}{\sum\limits_{i = 0}^{L - 1}{c_{l,{i + L},f}\left( {a_{i}b_{l,f}^{H}} \right)}}}\end{bmatrix}}},{{{where}l} \in {{\left\{ {1,\ldots,v} \right\}{and}v} \geq 1}}$

is a rank value, A=[a₀ a₁ . . . a_(L-1)], a_(i) is a

$\frac{P}{2} \times 1$

column vector whose one entry is 1 and remaining entries are 0, and P isa number of antenna ports in spatial domain (SD), B_(l)=[b_(l,0) b_(l,1). . . b_(l,M-1)], b_(l,f) is a Q×1 column vector, and Q is a number ofantenna ports in frequency domain (FD), C_(l) is a 2L×M matrixcomprising coefficients c_(l,i,f) with row index i∈{0, 1, . . . , 2L−1}and column index f∈{0, 1, . . . , M−1}; and the set of components Scomprises: Component 1: {a_(i)}_(i=0) ^(L-1) indicating L SD portselection vectors, and for each l∈{1, . . . , v}, Component 2:{b_(l,f)}_(f=0) ^(M-1) indicating M FD basis vectors, Component 3: Index(i*, f*) indicating an index of a strongest coefficient c_(l,i*,f*),Component 4: Bitmap {x_(l,i,f)} indicating indices of non-zero (NZ)coefficients of C_(l), Component 5: Amplitudes {p_(l,i,f)} of the NZcoefficients of C_(l), and Component 6: Phases {ϕ_(l,i,f)} of the NZcoefficients of C_(l).

In one embodiment, the first subset of components S1 includes Component2 and the second subset of components S2 includes Components 1, 3, 4, 5,and 6.

In one embodiment, the first subset of components S1 includes Components1 and 2 and the second subset of components S2 includes Components 3, 4,5, and 6.

In one embodiment, b_(l,f) is a FD port selection vector whose one entryis 1 and remaining entries are 0.

In one embodiment, L SD vectors are selected freely from

$\frac{P}{2}$

candidate SD vectors, and the selected vectors are reported via a

$\left\lceil {\log_{2}\begin{pmatrix}\frac{P}{2} \\L\end{pmatrix}} \right\rceil$

-bit indicator included in the CSI report.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims. None of the description in this application should be read asimplying that any particular element, step, or function is an essentialelement that must be included in the claims scope. The scope of patentedsubject matter is defined by the claims.

What is claimed is:
 1. A user equipment (UE) comprising: a transceiverconfigured to receive, from a base station, configuration information toreport channel state information (CSI), the configuration informationincluding information regarding a number of M frequency domain (FD)basis vectors to be selected and information regarding a total number ofN FD basis vectors; and a processor operably coupled to the transceiver,the processor configured to identify, based on the number of M FD basisvectors to be selected and the total number of N FD basis vectors,whether to report a first codebook index indicating the M FD basisvectors; wherein the transceiver is further configured to, in case thatit is identified to not report the first codebook index, transmit, tothe base station, a CSI report not including a precoding matrixindicator (PMI) value corresponding to the first codebook index.